Server process creates a UDP socket and binds to a local port. It
calls svc_register() routine to register its program number and
version with the local port mapper process. This process should have
been started as a daemon at system boot time. Server then waits for
requests.

Client program contacts the port mapper on the designated machine
using UDP. Gets port number for the server process.

Client program calls the client stub for the remote procedure (first
bin_date_1() and then str_date_1. Defaults for how
long to wait, how many times to retry, etc.

Transport protocol: Can use either UDP or TCP, Total size of
arguments must be less than 8192 bytes for UDP. rpcgen defaults to
UDP.

Exception handling:
If UDP is used and the client times it then it resends the request. If TCP
is used and an error occurs then the request is not resent.

Data representation: uses XDR.

Security. Set cl->cl_auth = (3 basic types). :

AUTH_NULL. null authentification (default)

AUTH_SYS. Unix authentification causes following fields to be
included with each RPC request: time stamp, name of the local host,
Default used by NFS (network file system).
client's effective user id, list of all client groups.